Radians 430-EHP is an electronic sound amplification earmuff. One independent microphone picks up and amplifies low sound level noises. Compact folding feature for easy storage. When sound levels exceed 86dB, the electronic circuit automatically protects at NRR 27 Amplifies Sound Protects Hearing On/Off Volume Control Padded Headband 200 Hours of Battery Life NRR 27 dB Package includes 1 black electronic earmuff